FIG. 25 shows a configuration of conventional electric discharge machining apparatus, and in FIG. 25, reference numeral 1 denotes an electrode, numeral 2 denotes workpiece, numeral 3 denotes a workpiece fixing device, numeral 4 denotes a X-axis motor, numeral 5 denotes a Y-axis motor, numeral 6 denotes a cross table which moves freely to X-axis direction and Y-axis direction by the X-axis motor 4 and the Y-axis motor 5. Numeral 7 denotes an ascending/descending shaft on which the electrode 1 having a specified shape is mounted and which is moved in the direction of Z-axis by a Z-axis motor 8, numeral 9 denotes a machining power supply for execution of electric discharge machining with electric energy between the electrode 1 and the workpiece 2, numeral 10 denotes an electrode exchange device which automatically exchanges the electrode 1 with a new one.
Reference numeral 11 denotes a NC tape/floppy disk as a medium storing a program for a machining sequence, data on an electrode such as an electrode reduction allowance, an electrode core gap, an electrode shape and the like, and data concerning workpieces such as a machining position and a machining depth, said data being used to decide how and what point of a workpiece to be machined are stored. Numeral 12 denotes a keyboard for complying a program and specifying the data concerning the electrode and workpieces.
Reference numeral 14 denotes a program outside inputting means for inputting data into a program from outside which displays a mistake in a program. This applies in case where if the program with machining sequence commands stored in an NC tape/floppy disk 11 has a mistake, and transfers the program to a memory 15. It also applies in a case where there is no mistake. Numeral 16 denotes a program compiling means which checks whether an input through the keyboard 12 has a mistake or not, transfers the information entered from the keyboard 12 to the program memory 15, in case where, there is no mistake in the entered information.
Reference numeral 17 denotes an electrode data outside inputting means for entering electrode data from outside which displays a mistake in the electrode data, in case where if the electrode data such as the electrode reduction allowance, the electrode core gap amount, the electrode shape and the like stored in the NC tape/floppy disk 11 has any mistake. It transfers the electrode data to an electrode data memory 18, in case where there is no mistake. Numeral 19 denotes an electrode data compiling means which checks whether an input through the keyboard 12 has a mistake or not, transfers the information entered from the keyboard 12 to the electrode data memory 18, in case where there is no mistake in the entered information.
Reference numeral 20 denotes a workpiece data outside inputting means for entering workpiece data from outside which displays a mistake in the workpiece data, in a case where if the workpiece data such as the machining position and the machining depth and the like of the workpiece 2 stored in and inputted from the NC tape/floppy disk 11 has any mistake, and transfers the workpiece data to an workpiece data memory 21, in case where, there is no mistake. Numeral 22 denotes a workpiece data complying means which checks whether an input from the keyboard 12 has a mistake or not, and transfers the information entered from the keyboard 12 to the workpiece data memory 21, in case where there is no mistake in the entered information.
Reference numeral 23 denotes an operation command analyzing means which executes an analysis of command data issued from the program memory 15, the electrode data memory 18, and the workpiece data memory 21 according to the machining program. Numeral 24 denotes an axis move control means which outputs data concerning the shaft generated by the operation command analyzing means 23 to each of the X-axis motor 4, Y-axis motor 5 and Z-axis motor 8 and drives the XY cross table 6 and the ascending/descending shaft 7. Numeral 25 denotes an electrode exchange device controlling means which transfers an electrode exchange command analyzed by the operation command analyzing means 23 to the electrode exchange device 10.
Reference numeral 26 denotes a program start key which gives an instruction for start of a program to the operation command analyzing means 23, numeral 27 denotes a NC control apparatus including the program outside inputting means 14, the program memory 15, the program compiling means 16, the electrode data outside inputting means 17, the electrode data memory 18, the electrode data compiling means 19, the workpiece data outside inputting means 20, the workpiece data memory 21, the workpiece data complying means 22, the operation command analyzing means 23, the axis move control means 24, and the electrode exchange device controlling means 25.
FIG. 26, FIG. 27 and FIG. 28 relate to an embodiment for the administration of a conventional machining program. Reference numeral 11 denotes the NC tape/floppy disk as a medium for storing a machining program, numeral 27 denotes the NC control apparatus, numeral 31 denotes a program manual in which machining contents of the machining program such as a number of workpieces, a number of electrodes and the like are written on paper, and numeral 32 denotes a program memory list displayed on a CRT of the NC control apparatus 27 and showing contents of the program memory 15. As above, in conventional electric discharge machining apparatus, a program is memorized in a floppy disk and the like as a medium for data entry, and all contents of the program is administered according to the program manual 31 in which all administrative instructions are written on a paper.
FIGS. 29A and 29B, FIG. 30 and FIG. 31 show a case of conventional machining where two workpieces each having two holes are machined with two electrodes. Reference numeral 41 denotes a workpiece W1, numeral 42 denotes a workpiece W2, numeral 43 denotes a rough electrode T11, numeral 44 denotes a finish electrode T12, P1 and P2 denote machining positions respectively. Reference numeral 45 denotes an embodiment of a machining program on the CRT display.
Next, the machining program 45 will be described referring to FIG. 30 and FIG. 31. Steps S1 to S30 show a rough machining step by the rough machining electrode T11 (43).
Step S2 shows to exchange an electrode to the rough electrode T11 (43). Step S3 indicates that the workpiece 41 set according to the workpiece coordinates W1 is machined at the machining position P1 in Step S3 to Step S10. Step S4 indicates that a workpiece is set according to the workpiece coordinates W1. Step S5 indicates that the subsequent commands for movement are issued with absolute values. Step S6 indicates movement to the machining position P1. A dielectric and a machining are set to ON in step S7. Step S3 indicates machining by 10 mm in the direction of Z-axis. After the machining, the dielectric and the machining are set to OFF in step S9. The electrode T11 (43) returns to a machining start position when contact is ignored in step S10.
Step S11 indicates that the workpiece 41 set according to the workpiece coordinates W1 is machined at the machining position P2 in steps S11 to S16. Step S12 indicates that the electrode moves to the machining position P2. A dielectric and a machining are set to ON in step S13. The workpiece is machined by 10 mm in the direction of Z-axis in step S14. After the machining in step S15, the dielectric and the machining are set to OFF. The electrode returns to a machining start position when contact is ignored in step S16.
Step S17 indicates that the workpiece 42 set according to the workpiece coordinates W2 is machined at the machining position P1 in steps S17 to S25. Step S18 indicates that the workpiece is set according to the workpiece coordinates W2(42). Step S19 indicates that the subsequent movement command is executed with absolute values. Step S20 indicates movement of the electrode to the machining position P1. A dielectric and a machining are set to ON in step S21. Machining is executed by 10 mm in the direction of Z-axis in step S22. The dielectric and the machining are set to OFF in step S23. The electrode returns to a machining start position when contact is ignored in step S24.
Step S25 indicates that workpiece 42 is machined at the machining position P2 in steps S25 to step S30. Step S26 indicates movement of the electrode to the machining position P2. A dielectric and a machining are set to ON in step S27. Machining is executed by 10 mm in the direction of Z-axis in step S28. After the machining in step S29, the dielectric and the machining are set to OFF. The electrode returns to the machining start position in step S30 when contact is ignored.
Step S31 indicates that machining for finishing is executed by the finish electrode T12 (44) in steps S31 to S60. Step S32 indicates exchange of the finish electrode T12 (44) with a new one.
Step S33 indicates that the workpiece 41 set according to the workpiece coordinates W1 is machined at the machining position P1 in steps S33 to S40. Step S34 indicates that a workpiece is set according to the workpiece coordinates W1. Step S35 indicates that the subsequent movement command is executed with absolute values. Step S36 indicates movement of the electrode to the machining point P1. A dielectric and machining are set on to ON in step S37. Machining is executed by 10 mm in the direction of Z-axis in step S38. After the machining in step S39, the dielectric and the machining are set to OFF in step S39. The electrode T11 (43) returns to the machining start position when contact is ignored in step S40.
Step S41 indicates that the workpiece 41 set according to the workpiece coordinates W1 is machined at the machining position P2 in steps S41 to S46. Step S42 indicates movement of the electrode to the machining position P2. A dielectric and a machining are set to ON in step S43. Machining is executed by 10 mm in the direction of Z-axis in step S44. After the machining in step S45, the dielectric and the machining are set to OFF. The electrode returns to the machining start position when contact is ignored in step S46.
Step S47 indicates that the workpiece 42 set according to the workpiece coordinates W2 is machined in steps S47 to S54. Step S48 indicates that the workpiece 42 is set according to the workpiece coordinates W2. Step S49 indicates that the subsequent movement command is executed with absolute values. Step S50 indicates movement of the electrode to the machining position P1. A dielectric and a machining are set to ON in step S51. Machining is executed by 10 mm in the direction of Z-axis in step S52. The dielectric and the machining are set to OFF in step S53. The electrode returns to the machining start position when contact is ignored in step S54.
Step S55 indicates that the workpiece 42 set according to the workpiece coordinates W2 is machined at the machining position P2 in steps S55 to S60. Step S56 indicates movement of the electrode to the machining position P2. A dielectric and a machining are set to ON in step S57. Machining is executed by 10 mm in the direction of Z-axis in step S58. After the machining in step S59, the dielectric and the machining are set to OFF. The electrode returns to the machining start position when contact is ignored in step S60. Step S61 indicates the end of execution of the program.
Next, another conventional electric discharge machining apparatus will be described. FIG. 32 is a block diagram showing the configuration of conventional discharge machining apparatus. Referring to FIG. 32, reference numeral 201 denotes an electrode, numeral 202 denotes a table, numeral 203a denotes a workpiece having a workpiece number 11, numeral 203b denotes a workpiece having a workpiece number 12. Numeral 203c denotes a workpiece having a workpiece number 13, numeral 204a denotes a workpiece fixing device for fixing the workpiece 203a on the table 202, numeral 204b denotes a workpiece fixing device for fixing the workpiece 203b on the table, numeral 204c denotes a workpiece fixing device for fixing the workpiece 203c on the table, numeral 205, 206 denote a motor for moving the table 202 in the X, Y directions, numeral 207 denotes a spindle with the electrode 201 mounted thereon, numeral 208 denotes a motor for moving the spindle 207.
Reference numeral 209 denotes a move controlling device for controlling movement of the motor 205, the motor 206 and the motor 208, numeral 210 denotes a memory outputting coordinates for machining, numeral 211 denotes a NC program including a workpiece exchange command, numeral 212 denotes a program analyzing device for analyzing the NC program 211, numeral 213 denotes a workpiece exchange controlling device for controlling exchange of a workpiece, numeral 214 denotes a memory storing a number of workpiece to be newly set.
Reference numeral 215 denotes a workpiece exchange device for executing the workpiece (workpiece 203a, workpiece 203b or workpiece 203c) fixed on the table 202 at a position for exchanging with the workpiece fixing device (workpiece fixing device 204a, workpiece fixing device 204b or workpiece fixing device 204c), and for carrying in the workpiece (workpiece 203a, workpiece 203b or workpiece 203c) with the workpiece fixing device (workpiece fixing device 204a, workpiece fixing device 204b or workpiece fixing device 204c) to the table 202, and for fixing on the table 202.
Reference numeral 216 denotes a computing device for computing coordinates for machining, numeral 217 denotes a memory for storing coordinates of the electrode 201 on a coordinate system in which a reference point of the workpiece fixing device 204 is an origin thereof, numeral 218 denotes a memory for storing coordinates for machining, an origin of which is a reference point of the workpiece fixing device 204, numeral 220 denotes a memory for storing data in the memory 217, when an exchange of workpiece starts, numeral 221 denotes a memory for storing coordinates for machining, when a workpiece is exchanged, and numeral 223 denotes an NC control device.
FIGS. 33A and 33B are views showing a position control for the electrode 201 and the table 202 in the computing device 216. G1 denotes a machining origin specific to the machining apparatus, G2 denotes a reference point on each of the workpiece fixing devices 204a, 204b, (g1, g2, g3) denotes coordinate values of G2 in the coordinate system in which the machining origin G1 is an origin thereof, workpiece off set in the coordinate system (hereinafter referred to as "G2 coordinate system") in which the reference point G2 is an origin, (x, y, z) denotes a coordinates of the electrode 201 in the G2 coordinate system, (X, Y, Z) denotes coordinate values of the electrode 201 in the coordinates for machining. Accordingly, an expression 1 is formed between the above values. EQU (X, Y, Z)=(x, y, z)+(g1, g2, g3) (Expression 1)
Next, operation will be described. The program analyzing device 212 starts to analyze the NC program 211 upon instruction to the program by an operator. The program analyzing device 212 reads out a workpiece exchange command from the NC program 211, issues the workpiece exchange command to the workpiece exchange controlling device 213, and stores the exchanged workpiece number in the workpiece exchange command in the memory 214. The workpiece exchange controlling device 213 outputs a workpiece exchange position movement command to the computing device 216. The computing device 216 stores coordinates in the memory 217 to the memory 220, and outputs a workpiece exchange position which is previously set in the memory 221 to the memory 210.
The move controlling device 209 outputs a movement command to the motor 205, the motor 206 and the motor 208 so that the table 202 and the spindle 207 are moved to the coordinates stored in the memory 210. The move controlling device 209 outputs an arrival signal to the computing device 216 when the table 202 and the spindle 207 arrives to the positions each specified by coordinates values stored in the memory 210. The computing device 216 outputs an exchange position arrival signal to the workpiece exchange controlling device 213 upon input of the arrival signal. The workpiece exchange controlling device 213 outputs a workpiece exchange start command to the workpiece exchange device 215 upon input of the exchange position arrival signal.
The workpiece exchange device 215 executes the workpiece 203a on the table 202 with the workpiece fixing device 204a upon input of the workpiece exchanging execute command. Then the workpiece exchange device 215 fixes the workpiece 203b having an exchanged workpiece number stored in the memory 214 with the workpiece fixing device 204b on the table by the workpiece exchange device 215. Thereafter, the workpiece exchange device 215 outputs a workpiece exchange end signal to the workpiece exchange controlling device 213, and the workpiece exchange controlling device 213 outputs a return command to the computing device 216. The computing device 216 memorizes coordinate values stored in the memory 220 to the memory 217, and figures out the sum of data stored in the memory 217 and the memory 218, proving the sum as output to the memory 210.
The move controlling device 209 outputs a movement command to the motor 205, the motor 206 and the motor 208 so that the table 202 and the spindle 207 are moved to positions each specified by coordinate values stored in the memory 210. The move controlling device 209 outputs an arrival signal to the computing device 216 upon arrival of the table 202 and the spindle 207 arrives to the positions each specified by the coordinate values stored in the memory 210. The computing device 216 outputs a return end signal to the workpiece exchange controlling device 213 upon input of the arrival signal. The workpiece exchange controlling device 213 outputs a workpiece exchange end signal to the program analyzing device 212 upon input of the return end signal.
In addition to the above, reference technical literatures relating to the present invention include Japanese Patent Laid-Open publication No. 70907/1992 disclosing "An arrangements data processing apparatus for a numerically controlled machining apparatus", Japanese Patent Laid-Open Publication No. 60924/1991 disclosing "A method of preventing an electrode from being mounted incorrectly, incorrect attachment of an electrode guide, Japanese Patent Laid-Open Publication No. 224555/1987 disclosing "A numerically controlled machining apparatus", and Japanese Patent Laid-Open Publication disclosing No. 111853/1986 disclosing "An electric discharge machining apparatus."
In the conventional electric discharge machining apparatus as described above, there are problems as follows. An operation must confirm contents of the program manual printed on paper for selecting an electrode and a workpiece according to a machining program, or must analyze a machining program, in case where the program manual is not near at hand, and as a result it is difficult to administer a program.
Also when setting electrode data, or workpiece data required for executing the program, an operator must check the program manual, or must analyze the machining program. As a result, an additional time is required for the operations, which lowers the workpiece efficiency.
Also sometimes the program may be executed even if an electrode and a workpiece as well as data concerning the electrode and the workpiece required for execution of the program have not been specified, and it is feared that, as a result, operation of the apparatus may go down during operation thereof in automatic mode at night, or under the similar conditions.
After a workpiece is exchanged by the workpiece exchange device, the position of workpiece fixing device is determined at the same position before exchanging to an electrode. Accordingly in a case where, even through a workpiece has a same shape, a position of a workpiece on the workpiece fixing device is different, relative position of the workpiece to the electrode is different compared with the position before exchanging. Then, in order to machine a workpiece at the same position before exchanging, the position of the electrode must be determined by manual operation, or an exclusive NC program must be used. Accordingly, it takes time, and labor. And, in case where the workpiece exchanged is larger than the previous one, it is feared that the electrode interferes with the workpiece or the electrode and the workpiece may be damaged, which prevents automatization of machining including an exchanging process of workpieces and makes the operational efficiency lower.